The cottage seems to float above everything. I think the front needs to be darker, especially near the bottom of the house. Or some rather obvious outdoor lights should be put in and beams cast appropriately.

The last traincar (Alien Vs. Redactor) looks like a billboard--the roof needs some highlighting or something to make it look less than empty space.

I echo chris by saying that you've probably already thought of these things, and also that the work is excellent so far.

What program did you use? How long have you been working on this particular image?